1. Field of the Invention
This invention relates to text editing systems which can be implemented by magnetic bubble domain devices or by charge coupled devices, and more particularly to a dynamic shift register text editing system which will perform all data manipulation functions with a constant sequence of applied drive pulses.
2. Description of the Prior Art
Current keyboard text editing facilities use mechanically accessed magnetic media for storage and semiconductor devices for editing. Problems of speed discrepancy and synchronization dictate the use of a semiconductor random-access memory as a buffer. This complex system requires considerable semiconductor logic devices for control. As will be appreciated, this type of approach requires several different technologies and necessitates suitable interfaces for these different technologies.
Magnetic bubble domain technology provides inexpensive, non-volatile, non-mechanical storage devices suitable for large capacity memories. Indeed, considerable attention has been paid to the memory applications of magnetic bubble domains, as is amply reflected in the published literature. However, bubble domains also offer switch capabilities as can be seen by referring to U.S. Pat. No. 3,701,125, which describes an on-chip memory-decoder system.
Some prior art in magnetic bubble technology describes reordering of data bits represented by bubble domain patterns. For instance, reference is made to the dynamically ordered magnetic bubble domain memories described in U.S. Pat. No. 3,670,313 and U.S. Pat. No. 3,797,002. Additionally, reference is made to U.S. Pat. No. 3,701,132. All of these prior art patents describe the relocation of bubble domain data bits in systems where the bubble domains are propagated by the use of a reorienting, in-plane magnetic field. However, the technique for reordering data in these prior art patents is based on magnetic field reversal or stoppage. This presents a significant difficulty in synchronization of data movement and in the design of circuits for the movement of bubble domains in an entire chip, where the reversal or stoppage of the magnetic field, intended for one part of the chip, nevertheless has an effect on all devices performing various functions in the magnetic chip. This means that specialized shielding mechanisms and/or propagation elements have to be designed in order to maintain control of the data at locations other than those where a reordering of data is to take place, and also that other processing functions requiring forward field are interrupted. Additionally, the use of a field reversal or stoppage of the magnetic field requires more complex peripheral electronic control circuits and does not permit the use of tank-circuit drives in order to obtain a large magnetic field energy which would be required for large storage capacity.
In addition to the shortcomings described above, the prior art does not take into consideration the introduction of a gap in the data bits which may be produced by different manipulative functions performed on the data. In a text editing system, the flexible manipulation of a gap which is produced when, for instance, data is deleted from a line of text, must be achieved. In the prior art patents where only the order of data is important, no attempt is made to adjust any gap, nor is there any concern about such a gap. In this regard, it should be noted that field reversal does not allow local control in a specified portion of the magnetic chip and is therefore not a technique which can be used to adjust a gap.
In the system proposed herein, these problems are solved using a novel text editing system. Additionally, a constant rotating magnetic field (of substantially constant amplitude) is used at all times in the proposed bubble domain system. Because this is done, the principles shown herein for magnetic bubble domains can be applied directly to charge coupled devices to achieve a corresponding system using charge coupled devices for the dynamic shift register storage. If field reversal were required, as is the case in the prior art, charge coupled devices could not be used. Consequently, the present system embodies broad principles which are applicable both to the magnetic bubble domain technology and to charge coupled device technology which is also a dynamic shift register type of storage.
As will be apparent, the proposed system offers flexible storage structures for facilitating the input, output, retrieval, and revision of data. Additionally, a wide range of data manipulation functions is achieved and the system provides for ready timing controls and character encoding.
Accordingly, it is a primary object of the present invention to provide a text editing system using dynamic shift registers, which does not require a reversal or stoppage of the drive fields applied for manipulation of data.
It is another object of this invention to provide a text editing system using magnetic bubble domains.
It is a further object of this invention to provide a text editing system using magnetic bubble domains wherein the magnetic drive field need not be stopped or reversed.
It is a still further object of this invention to provide a magnetic bubble domain text editing system which is totally on the magnetic chip.
It is a still further object of this invention to provide a text editing system which can be implemented in either magnetic bubble domain technology or charge coupled device technology.
It is another object of this invention to provide a magnetic bubble domain text editing system which can be used to perform editing on a character by character basis.
It is another object of this invention to provide a dynamic shift register text editing system using a single technology, which minimizes interface complexity.
It is a further object of this invention to provide a bubble domain text editing system which permits simultaneous operation of many functions while localized switching functions are occurring at the same time.
It is another object of this invention to provide a text editing system which is flexible and which can be adapted and designed to the user's own requirements.
It is still another object of this invention to provide a text editing system wherein the devices for editing and sorting data and the devices for storing information are compatible in design and can be hosted in the same storage medium to realize an integrated circuit.